Image-reproducing plate and cylinder assembly



Feb. 9, 1954 J. A. BOYAJEAN, JR 2,668,498

IMAGE-REPRODUCING PLATE AND CYLINDER ASSEMBLY Original Filed July 24,1948 2 Sheets-Sheet 1 ATTO R NEY JOHN A. BOYAJEAN Feb. 9, 1954 J. A.BOYAJEAN, JR

IMAGE-REPRODUCING PLATE AND CYLINDER ASSEMBLY Original Filed Jul 24,1948 2 Sheets-Sheet 2 INVENTOR. JOHN A. BOYAJEAN ATTORNEY Patented Feb.9, 1954 IMAGE-REPRODUCING, PLATE AND CYLINDER ASSEMBLY John A.,Boyajean,J r., Upper Montclair, N. J assignor to Fairchild Camera and InstrumentCorporation, a corporation of Delaware Original application July 24,1948, Serial No. 40,595. Divided and this application February 9, 1951,Serial No. 210,170

3 Claims. (Cl. 101 --415.1)

This invention relates to image-reproducing plate and cylinderassemblies and, while it is of. general application, it is particularlyuseful as a component or subassembly of a machine for produeing screenedrelief pattern plates of the type described in applicants copendingapplication, Serial No. 40,594, now Patent 2,575,546.

This application is a division of applicants copending application,Serial No. 40,595, filed July '24, 1948, entitled Image-ReproducingPlate and Cylinder Assembly, now Patent 2,641,183.

In aforesaid copending application, Serial No. 40,594,v now Patent2,575,546, there is described a machine designed and intended to be usedin the place of well-known photo-chemical processes for making platesfrom photographic prints, negatives, or other images for reproduction byprinting or like processes. In general, that machine comprises a pair ofsynchronously rotatable cylinders for individually supporting a plateand an image sheet and a pair of reciprocable carriages individuallyincluding a pick-up system and a plate-deforming tool for respectivelyscanning the image sheet cylinder and the plate cylinder. The machinealso includes means responsive to the output of the pick-up system foractuating the tool, means for reciprocating the carriages synchronously;and an electrical screen generator driven synchronously with thecylinders and connected to modulate the output of the pick-up system.

It is an object of the present invention, therefore, to provide a newand improved imagereproducing plate and cylinder assembly which, whileof general application, is particularly useful as a sub-assembly in amachine of the type described.

It is another object of the invention to provide a new and improvedimage-reproducing plate and cylinder assembly of maximum simplicity inconstruction, of maximum facility in assembly and disassembly, andcapable of use by an unskilled operator.

It isanother object of the invention to provide a new and improvedimage-reproducing plate and cylinder assembly in which the plate to beformed is securely fixed to its supporting cylinder and tensioned toprovide a smooth surface upon which the image to be reproduced isformed.

In accordance with the invention, there is prnvided for use in a machineof the type described an image-reproducing plate of flexible defprmable'material having notched ends with parallel preformed tensioning flangesat either end thereof and a supporting cylinder mecha! nism havingprovisions supporting it for rotation. The cylinder mechanism has alongitudinal slot extending to its periphery and notched complementarilyto the notched plate and two groups of interleaved tensioning membersdisposed in the notches of the slot and movable transversely thereof inopposite directions. The groups of tensioning members include two seriesof slots disposed to receive the flanges of the plate. The cylindermechanism also includes means for moving the tensioning memberstransversely of the slot to tension the plate about the cylinder.

For a better understanding of the present invention, together with otherand further objects thereof, reference is had to the followingdescription taken in connection with the accompanying drawings, and itsscope will be pointe out in the appended claims.

Referring now to the drawings, Fig. l is a schematic perspective view ofa machine of the type described including a plate and cylinder assemblyembodying the present invention; Fig. 1A is a fragmentary view of thecylinder supporting shaft of the machine of Fig. 1; Fig. 2 is aperspective view of a blank printing plate embodying a feature of theinvention; Fig. 3 is a fragmentary elevation of the plate and cylinderassembly of the invention; Figs. 4 and 5 are enlarged fragmentarycross-sectional views along the line t 4 of Fig. 3, showing theplate-tensioning members of the cylinder in open and closed positions,respectively; while Fig. 6 is an end view of the cylinder of Fig. 3,showing the operating member by which the plate-tensioning members areopened and closed.

Similar reference characters refer to similar parts throughout the viewsof the drawings.

Referring now more particularly to Fig. 1, there is illustratedschematically a machine for producing on a plate from an image sheet ascreened relief pattern suitable for image reproduction by printingprocesses. This machine includes an electric driving motor 20 which di--rectly motivates all moving parts of the machine except the reciprocableheated stylus. The motor includes a shaft 2] connected as by a flexiblecoupling 22 to a shaft 23 on the end of which is mounted a worm 24. Worm24 meshes with a worm Wheel 25 fastened to a shaft 26, on which ismounted a flywheel 21. The flexible coupling 22 mechanically filters orsmoothes out any pulsation which the rotation of the motor may possess,while the flywheel ensures pulsationless rotation of shaft 26,regardless of irregularities that might otherwise be produced throughimperfections in the worm and worm wheel.

Shaft 26 has mounted. on its left-hand end a metallic disc 23 having anumber of equally spaced teeth 29 formed on its periphery. This discoperates in conjunction with an insulated metallic ring 30 havingequally spaced teeth (not shown) formed on its inner periphery, the ringand disc constituting an electrostatic type of alternatingvoltagegenerator. The disc and ring comprise a half-tone screen generatingdevice which provides an alternating voltage which is used to provide ascreen for the subject copy.

On the right-hand end of shaft 26 is an overrunning (one-way drive)clutch |9, the driving element of which is secured to shaft 26, and thedriven element of which is secured to a shaft 3|. This clutch allows flywheel 21 to decelerate when motor 20 is ole-energized, without imposingan undue back load on the speed-reducing worm and worm wheel, and alsoallows the operator manually to rotate shaft 3|, if desired.

Shaft 3| comprises the drive shaft for the image-reproducing plate andsupporting cylinder assembly of the invention including a supportingcylinder mechanism 32, this cylinder having provisions for supporting itfor rotation, for example, a shaft 33. The left-hand end of shaft 33 isdetachably secured to drive shaft 3| by a separable connection 34, whichis shown in greater detail in Fig. 1A. Thus, the right-hand end of shaft3| and the left-hand end of shaft 33 are milled to half rounds, the endof shaft 3| carrying an attaching pin 35. This pin is adapted to extendinto a hole 36 formed in the half-round end of shaft 33, thus to connectthe two shaft ends. A slidable collar 31 is movable from its full to itsdottedline position over the half-round ends of the shafts detachably tosecure these ends together, any suitable means being provided to holdthe collar in its locking position. The right-hand end of shaft 33(Fig. 1) is detachably secured as by another coupling 34 to theleft-hand end of a shaft 38, the right-hand end of which carries aclutch disc 38. A second cylinder, generally indicated at 40, isprovided to support the subject copy and this cylinder is mounted on ashaft 4|. On the left-hand end of shaft 4| is a clutch disc 42 which isa complement of disc 39, either of these discs, for example, disc 39,being movable relative to the other as by a lever system 43 to engagethe discs and thus form a driving connection between shafts 38 and 4|.It may now be seen that when motor 23 is energized, shafts 3|, 33, 38,and 4| are all driven at the same rate of speed so as to effect rotationof plate-supporting cylinder 32, and the copy-supporting cylinder 40.

Underlying cylinders 32 and 43 are a pair of guide rods or ways 44 and45, which are parallel to the common axis of the two cylinders. Theseguide rods slidably support a scanning carriage generally indicated at46, and a deforming tool or stylus carriage generally indicated at 41,these carriages being respectively juxtaposed to copysupporting cylinder40, and plate-supporting cylinder 32.

Scanning carriage 46 includes a bracket 48, or the like, which issupported by guide rods 44 and 45 and has a rearwardly extendingplatform 49 which supports a scanning head generally indicated at 50.Carriage 41, in turn, includes a bracket having a rearwardly extendingplatform 52, on which is mounted the stylus head, generally indicated at53. Head 53 includes a base 54 which is pivotally attached in anysuitable manner to platform 52; a holding magnet (not shown) which whenenergized swing the cutter-head into proper operating position relativeto cylinder 32 against the action of a retracting spring 56, and astylus and driving motor therefor, generally indicated at 51.

The scanning and stylus carriage brackets 48 and 5| are driven by a belt58 which is trained about drive and guide pulleys 59 and 60,respectively, the bracket 5| being fixedly attached to the belt 58 andthe bracket 48 being releasably attached thereto by an internal clutch(not shown) actuated by an adjustable knob 48a. Drive pulley 59 isfastened to one end of a shaft 6|, whose other end carries a worm wheel62, meshing with a Worm 63. This worm is mounted on the lower end of ashaft 64, whose upper end carries a worm wheel 65 which meshes with aworm 66 mounted on shaft 3|. It may now be seen that, as shaft 3| isdriven by motor 2!], drive pulley 59 is rotated at a low R. P. M.through the reduction afforded by worm 66, Worm wheel 65, worm 63, andworm wheel 62, accordingly to drive belt 58 at a very low rate of speed,thus to move the scanning and stylus heads 50 and 63 along pathsparallel to the common axis of cylinders and 32.

As scanning head scans the subject copy, for example, a photographicprint 61 on cylinder 43, it transmits a succession of signals whoseamplitudes vary proportionally to the shade or tonal values of theprint. At the same time, the gen erator 29 produces an alternatingvoltage of screen frequency, for example, 350 cycles/second. This screenvoltage is amplified and varied in amplitude or modulated by the signalsdeveloped by the scanning head 50 and fed to the stylus motor 51 whichoscillates its stylus 51a at the frequency of the screen voltage andwith an amplitude varying with the image signals from the scanning head58. Stylus 51a, which is heated (by means not shown) to a temperature inexcess of 1000 F., has a tapered point and burns a pit in animage-reproducing plate 68 mounted on cylinder 32 at each stroke, thedepth and surface area of successive pits accordingly being a functionof the amplitude of successive signals transmitted by the scanning head.Accordingly, there are formed in plate 68 a large number of regularlyspaced pits of areas varying with the shade values of the subject copyor print 61, leaving islands therebetween forming the printing surfaceand also of areas varying with the shade values of the print 61.

It is desirable that the pits formed in adjacent lines of plate 68 be instaggered relationship to provide the half-tone screen effect whichcharacterizes the conventional photo-engraving process. To this end, thering 33 of alternatingvoltage generator 29 is mounted on one end of ashaft 69, the other end of which carries a pulley 10. Trained about thispulley is a drive cable 1| which is supported by guide pulleys 12 and13, and is trained about a third guide pulley 14. One run of cable 1| isattached to a post 15 fastened to stylus bracket 5|, while the other endis returned to post 15 through the intermediary of a stiff spring 1|a.Thus, as the stylus is driven to the left, it in turn drives cable 1|,causing pulley 10 and accordingly shaft 69 and ring 30 to rotate veryslowly. This rotation of the ring 30 relative to the stylus carriage 41shifts the phase of alternating voltage developed'by generator 23 byone-half cycle for each complete revolution of the cylinder 232; therebyto produce the staggered pit relationship referred to.

The above description of the machine shown in Fig. 1 is included hereinto clarify what follows. For a detailed description of the features ofconstruction and operation of this machine, reference is made to theaforementioned copending application, Serial No. 40,594.

the hot stylus 51a, at each stroke thereof. In

other words, the portion of the plate surrounding the pit formed by thestylus must be left intact, as it is the plate surfaces between the dotsor pits formed by the stylus that carry the ink where the plate is usedas a half-tone or roto- 'gravure plate. These same. plate surfaces mustalso be preserved with the greatest definition possible where the plateis used as a rotogravure printing plate. It accordingly follows that theplate must not only have certain characteristics, but also must beproperly supported during the "engraving operation if the picture to beprinted by the completed plate is to have the sharp definition and tonegradation required. Thus, where the blank plate is made of a highlycombustible material, such as, for example, nitro-cellulose, it .isnecessary that the thermal decomposition. of the material caused by theengagement thereof by the hot stylus be narrowly controlled, not only toattain the aforementioned definition, but also to avoid any danger of aserious fire. To this end, the machine described includes a sub-assemblyor component part thereof the plate and cylinder assembly now to bedescribed in greater detail.

In Figs. 3-6, inclusive, there is shown such a plate and supportingcylinder assembly embodying theinvention. The cylinder is generallyindicated at III and comprises opposite end hubs H2 and H3, which may beattached to shaft 33 in any suitable manner. The cylinder III and hubsH2 and H3 are formed of a metal having good heat-conducting properties,such as steel or aluminum. Disposed between and secured to these hubs isa cylindrical shell H4, the outer surface of which constitutes theplatesupporting surface of the cylinder. Extending through shell I I4 isa slot, generally indicated at I i5, having oppositely extending notchedsections H6 and I H, the slot extending throughout the length of theshell.

As is shown in Figs. 3 and 4, two groups of interleaved tensioning armsH8 and H are pivotally mounted on shaft 33 and thus are pivoted aboutthe axis of cylinder IH. Each of these arms includes a hub, such as hubE of arm H8, whereby the arm is supported on shaft 33, a plate-clampingfinger I2 I, and a foot I22. Each of arms H9 correspondingly includes ahub I23, a finger I 24., and a foot I25. Thus, the finger and foot ofeach arm II8 are displacedlaterally by the thickness of their hub I20from and are opposed to the finger I 24 and foot I25 of thecomplementary arm IIO. Finger I2I has an inclined slot I26 formedtherein, finger I24 having an oppositely inclined slot I21. These slotsI25 and I2I- form acute angles of the order of 30 with tangents to thesurface of cylinder III at their respectiveentrances. The end of eachanfel'l lfl wtFig. 3).;extendsi into anotchxsection H6 of slot II 5,while the end of each finger l-24 extends into a notch section I I! ofslot I I5, these two groups of finger ends being movable transversely ofthe slot I I5 in opposite directions, such movement being limited by thecircumferential extent of the notched slot. The groups of arms H8 and H0are pivotally actuated in opposite directions by an elongated cam 528(Fig. 4) whose opposite ends are fastened respectively to operatinglevers 84- and 85. Thus, when these levers are swung from their openposition to their closed Fig, 3 position, cam I28 is rocked from itsFig. l position to its Fig. 5 position, this movement of the cam rockingarms H8 clockwise and arms H9 counterclockwise. This, of course, swingsfingers I2] and I24 to their closed position shown in Fig. 3.

In Fig. 2 there is shown a blank image-reproducing plate 68 which, asindicated hereinbefore, is formed of a flexible deformable material,specifically, one which, upon ignition, will continue to burn withoutexternally supplied oxygen, provided the material is maintained abovethe ignition temperature. An example of such a material is oneconsisting in substantial part of a nitro-cellulose such as cellulosenitrate, although other materials having the aforementioned property maybe used. Plate 68 comprises a body portion I04, the under surface I05 ofwhich is finished to a true and flat surface. The upper or outer surfaceof the plate may or may not be polished, as desired, but it is finishedto a surface which is sufficiently flat and true for printing purposes.The opposite ends of the plate 68 .i' are notched, forming groups offingers I29, I30

on either end thereof, the fingers of the two groups being staggeredwith respect to each other and proportioned to overlie the fingers I2I,I24, respectively, of the cylinder mechanism. The groups of fingers I20, I30 are formed with parallel preformed reversely bent flanges I20a,I30a, respectively, forming with the plate body I04 acute angles ofapproximately 30 corresponding to the angles of the slots I 20, I21 ofthe fingers I2I, I24, respectively. The flanges I20a,

I30a are of substantial rigidity and constitute provisions fortensioning the plate 08 about the cylinder. The flanges I29a, I30a areso formed as to leave small radii I29!) and I301; of substantially thesame value as the corresponding radii of the points of fingers I2I, I24.Furthermore, the distance between planes which are normal to plate 08and which are respectively tangent to radii I29?) and I301) ismaintained as nearly uniform as practicably possible, so that the edgesof the plate are parallel.

When the plate 50 is mounted on the cylinder, the flange I29a on each offingers I20 is inserted into the slot I 26 of arm finger I2I, while eachflange I30a of fingers I30 is inserted into the slot I21 of arm fingerI24, whereupon the plate takes the position shown in 4. It may then beseen that when cam shaft is rocked, as hereinbefore described, theopposed groups of tensioning arms H0, H9 are moved into the Fig. 5position, thus tensioning plate 68 tightly about the cylinder surface.This provides nearly tangential movement of the ends of the plate 50 andhas a low value of frictional resistance upon tensioning. Final movementof cam shaft 128 to the limit of its closing movement stretchesthe platebody so that the plate body is actually elongated. The effect of this isto perfect theengagement of all portions of the under surface I05of theplate body with. the surface of the; cylinder.

therebysstablishins.there etwecn. as som 1 w transfer relationship aspossible. While the plate i tensioned well below its elastic limit, thetensioning has the further effect of smoothing out any ripples or wavesin the plate so that the portion of the outer surface of the plate thatis to be operated on by the hot stylus is as nearly exactly cylindricalas practicably possible. This condition of the outer surface of theplate assures uniformity of the depth of pits formed by the hot stylusover areas of the same tone value, so that uniform tone is produced bythe plate during the printing operation.

By preforming plate flanges I29 and I30 in such a way as to provideradii I291) and I301) complementary to radii of the points of fingers I2I, I24, undue stress is not localized at the plate edges when the plateis tensioned. Furthermore, by providing the plate radii referred to, itis not necessary to crease sharply the plate at edges thereof, whichmight weaken the plate.

The perfection of the heat transfer relation between the under surfaceof the plate and the supporting surface of the cylinder is attained bothby reason of the intimate engagement therebetween due to the finishedunder surface of the plate. This relationship between the plate andcylinder is important because of the nature of the plate material. Inother words, the intense heat created in the plate by the engagementthereof with the hot stylus must be conducted away from the plate asrapidly as possible or else the plate would continue to burn. It isequally important rapidly to conduct the heat from the plate in orderthat the individual pits formed by the hot stylus do not enlarge bycontinued combustion of the material forming the pit walls, after thewithdrawal of the hot stylus. This is particularly true where a screensize of 120 or greater is being out.

It has been found that by exerting approximately tangential tension onthe plate at either end substantially all portions of the plate bodybetween radii I29?) and I301) are stretched, thus attaining the desiredtensioning throughout all portions of plate 58 which assures theintimate engagement between the under surface of the plate and thesurface of the cylinder. It might be noted that the under surface of theplate, in addition to perfecting the heat transfer relation referred to,also facilitates relative movement between the finished plate surfaceand the cylinder surface which, of course, occurs as the plate isstretched.

The importance of this close, tight engagement between the under surfaceof the blank plate and the supporting surface of the cylinder and theresultant heat transfer relationship effected thereby is furtheremphasized when it is pointed out that the thickness of the body of theplate may be of the order of 0.030 inch. With a plate as thin as this,it becomes clear that there is insuiiicient material mass adjacent thepits formed .by the hot stylus to conduct the heat away from the sidesof the pits with sufficient rapidity to preclude continuing combustionat the pit walls, as would enlarge the size of the pits, and perhapscause destruction of the plate. This is particularly true where thestylus penetration is maximum, as it would be where highlight tonevalues are being reproduced. Thus, the specific characteristics andproperties of the blank plate combine in an advantageous manner with thestructural and functional characteristics or feaiicient and effectivecom-ponent'of the machine.

noted-hereinbeforashaf't 33 (Fig. 1) of cylinder 32 is detachablysecured to shafts BI and 38 by the separable connections 34. By somounting the cylinder in the machine, and by providing the user of themachine with two cylinders, it is possible for the operator to set up acylinder and plate unit at a station remote from the machine while themachine is operating on another cylinder and plate unit mounted in themachine. Inasmuch as the cylinder and plate unit in the machine can bedetached therefrom and the second cylinder and plate unit thereafterfastened to shafts 33 and 38 in a very considerably less amount of timethan it takes to mount a blank plate on the cylinder, it may be seenthat valuable time is saved through the provision of the detachablemounting for the cylinder, and through the provision of a plurality ofcylinder and plate units. Further, and perhaps even more important, isthe fact that where an extra cylinder is available, the operator doesnot have to handle the blank plate close to the hot stylus and in therelatively confined space adjacent the cutterhead. This, of course,precludes the danger of the operator being burned by the stylus, or theplate coming in contact therewith and being damaged or spoiled. Ofcourse, it is much easier to mount the plate on the cylinder when thecylinder is out of the machine.

While there has been described what is at present considered to be thepreferred embodiment of the invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madetherein without departing from the invention, and it is, therefore,aimed in the appended claims to cover all such changes and modificationsas fall within the true spirit and scope of the invention.

What is claimed is:

1. In a machine for producing on a plate from an image sheet a screenedrelief pattern suitable for image reproduction by printing processes, animage-reproducing plate and cylinder assembly comprising: animage-reproducing plate of flexible deformable material having notchedends with parallel preformed tensioning flanges at the ends of thenotch-separating portions thereof and with notches on the two endsstaggered with respect to each other; a supporting cylinder mechanismhaving provisions supporting it for rotation and a longitudinal slotextending to the periphery thereof and notched complementarily to saidplate; two groups of interleaved tensioning members disposed in thenotches of said slot and movable transversely thereof in oppositedirections; said groups of tensioning members including a pair of seriesof slots disposed to receive said flanges of said plate; and means formoving said tensioning members transversely of said slot to tension saidplate about said cylinder.

2. In a machine for producing on a plate from an image sheet a screenedrelief pattern suitable for image reproduction by printing processes, animage-reproducing plate and cylinder assembly comprising: animage-reproducing plate of flexible deformable material having notchedends with parallel preformed tensioning flanges at the ends thereof andwith notches on the two ends staggered with respect to each other; asupporting cylinder mechanism having provisions supporting it forrotation and a longitudinal slot extending to the periphery thereof andnotched complementarily to said plate; two groups of interleavedtensionmg arms pivotally.mountedabout. the axis of said cylinder andextending into said slot with their ends movable transversely of saidslot in opposite directions, said groups of tensioning members includinga pair of series of slots disposed to receive said flanges of saidplate; and an elongated cam for pivotally actuating said groups ofmembers in opposite directions to tension said plate about saidcylinder.

3. In a machine for producing on a plate from an image sheet a screenedrelief pattern suitable for image reproduction by printing processes, animage-reproducing plate and. cylinder assembly comprising: animage-reproducing plate of flexible deformable material having parallelpreformed tensioning flanges at the ends thereof; a supporting cylindermechanism having provisions supporting it for rotation and alongitudinal slot extending to the periphery thereof; two groups ofinterleaved tensioning arms pivotally mounted about the axis of saidcylinder 10 and extending into said slot with their ends movabletransversely of said slot in opposite directions, said groups oftensioning members including a pair of series of slots disposed to receive said flanges of said plate; and an elongated cam for pivotallyactuating said groups of members in opposite directions to tension saidplate about said cylinder.

JOHN A. BOYAJEAN, JR.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 348,736 Goodwin Sept. 7, 1886 657,358 Perry Sept. 4, 19002,109,152 Meisel Feb. 22, 1938 2,157,621 Neilson May 9, 1939 2,194,424Grupe Mar. 19, 1940

